Hydraulic control system

ABSTRACT

A hydraulic control unit includes a plurality of radial pump units driven by a common drive means. Each of the pump units is provided with an individual control assembly in the form of a control lever for rotating a cam which adjusts the eccentricity of a guide ring coupled to the radial pistons of a pump unit. In this way, the direction and magnitude of flow from the pump is controlled, being fed to or from the pump through a pair of conduits. The conduits are connected to a valve which, in response to the direction of flow in the conduits, is shifted to direct fluid flow in one of two directions through a hydraulic work unit. The valve also serves to direct fluid received from the work unit to a common condenser.

United States Patent Becker 1 1 HYDRAULIC CONTROL SYSTEM [75] Inventor: Lester .1. Becker, Alexandria, Va.

[73] Assignee: Kate C. Lainof, Alexandria, Va.

[22] Filed: Mar. 25, 1971 [21} Appl. No.: 127,961

Related U.S. Application Data [62] Division of Ser, No. 858,290, Sept, 16, 1969, Pat,

[52] U.S. Cl. 91/497 [51] Int. Cl. 1 01b 13/06 [58] Field of Search 91/497, 498, 492; 417/426, 417/315 [56] References Cited UNITED STATES PATENTS 1,861,116 5/1932 Ernst 417/217 1,937,019 11/1933 Hamill 417/426 2,420,806 5/1947 Anderson. 417/315 2,429,368 10/1947 Quiroz 91/497 2,646,755 7/1953 Joy 91/497 2,716,944 9/1955 Ferris 91/492 2,716,948 9/1955 Cuny 91/491 2,728,302 12/1955 Ferris 417/315 2,772,755 12/1956 Nallinger et a1. 91/492 2,963,983 12/1960 Wiggermann M 91/65 [4 1 July 1, 1975 Primary Examiner-William L. Freeh Attorney, Agent, or FirmRobert l. Lainof [57] ABSTRACT A hydraulic control unit includes a plurality of radial pump units driven by a common drive means. Each of the pump units is provided with an individual control assembly in the form of a control lever for rotating a cam which adjusts the eccentricity of a guide ring coupled to the radial pistons of a pump unit. in this way, the direction and magnitude of flow from the pump is controlled, being fed to or from the pump through a pair of conduits. The conduits are connected to a valve which, in response to the direction of flow in the conduits, is shifted to direct fluid flow in one of two directions through a hydraulic work unit. The valve also serves to direct fluid received from the work unit to a common condenser.

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268 INVENTOR 208A LESTER J. BECKER 12 n Mir A TORNEY HYDRAULIC CONTROL SYSTEM The present application is a division of my prior copending application Ser. No. 858,290, filed Sept. 16, I969, now U.S. Pat. No. 3,601,986.

BACKGROUND OF THE INVENTION This invention relates to hydraulic control systems and, more particularly, to hydraulic systems employing radial pump units.

It is frequently desirable in hydraulic control systems to provide a variable quantity of fluid under pressure to a hydraulic work unit, such as a hydraulic cylinder, motor, or the like. To this end, it has been suggested in the prior art that a variable delivery pump be employed for providing the variable flow of hydraulic fluid. Radial piston pumps have been particularly suitable for this purpose. Such pumps employ a rotor having a plurality of radial bores within which pistons are provided in conjunction with guide means for regulating the stroke of the pistons. If the guide means is made eccentric with respect to the axis of rotation of the rotor, the pis tons will be caused to reciprocate radially of the rotor within the bores to effect a pump action. The extent of eccentricity will regulate the volume of flow provided by the pump.

In prior art hydraulic control systems employing variable delivery pumps of the radial-piston pump type, it was necessary, where a plurality of hydraulic work units were employed, to provide a plurality of radial pumps with separate drive means for each pump; or, when a single drive motor was employed, it was necessary to employ elaborate gearing to drive each of the radial pumps separately. It is also difficult in such prior art systems to control the direction of fluid flow to the hydraulic work unit from the radial pump units. In addition, the means provided for adjusting the eccentricity of prior art radial pump units have tended to be unduly complex or inconvenient to control.

SUMMARY OF THE INVENTION It is accordingly an object of the present invention to provide an improved hydraulic control system employing radial pump units.

More particularly, it is an object of the invention to provide a hydraulic control system employing radial pump units which is versatile in application, simple to control, easy to maintain with a minimum inventory of spare parts, and economical.

It is a further object of the invention to provide a hydraulic control system in which a plurality of radial pump units are driven on a single shaft and powered by a single prime mover rotating in one direction. An additional object relates to the provision, in a system of this character, of control means, capable of remote operation, for independently controlling the radial pump units for variable output in either direction. A related object is the provision of a single control unit for each radial pump unit for controlling the direction of flow from the pump unit regardless of the direction of prime mover rotation and the direction of flow from the remaining pump units and for acting as a metering valve for flow control so that flow can be controlled from zero to full capacity of the pump unit.

Another object is the provision of a control valve in association with a radial pump unit for automatically directing fluid through a hydraulic work unit for the proper direction as indicated by the control. A related object is the provision of a control valve in a system of the aforementioned character which acts as a locking valve to hold a cylinder of a hydraulic work unit in any given position.

Briefly, according to the present invention, a single prime mover drives rotor means including a plurality of radial pump units, each having a plurality of radial bores and a piston in each bore. Each of the radial pump units has individual control means for adjusting the radial stroke of the pistons of each unit so that the direction and magnitude of fluid flow in a pair of conduits leading to and from the radial pump unit is controlled independently of the direction and magnitude of flow in conduits associated with the remaining pump units and the direction of rotation of the rotor means. The system includes special valve means coupled to the conduits including a valve body normally biased to a mid-position and responsive to fluid flowing from one of the conduits for directing fluid through a hydraulic work unit in one direction and responsive to fluid flowing from the other of the conduits for directing the fluid through the hydraulic work unit in the opposite direction. More specifically, the special valve includes a valve body or spool having a plurality of valve recesses and a pair of end chambers associated with springs which bias the valve body and maintain it in a midposition in the absence of fluid flowing from either conduit. When fluid is received from either conduit, the pressure thereof is applied against the valve body to shift it and open a fluid path to the hydraulic work unit in the desired direction. In order to control the magnitude and the direction of fluid flow from each of the ra dial pump units, individual control means comprising a control shaft and a cam for adjusting the eccentricity of a guide ring in the pump unit is provided.

The foregoing and other objects, advantages, and features of the invention and the manner in which the same are accomplished will become more readily apparent upon consideration of the following detailed description of the invention when taken in conjunction with the accompanying drawings, which illustrate a preferred and exemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram of a hydraulic control system of the invention;

FIG. 2 is a schematic section view of a hydraulic control unit of the invention generally taken along line 2-2 of FIG. 4 with conduits and control assemblies displaced to aid in the explanation of the invention;

FIG. 3 is a schematic section view taken generally along line 33 of FIG. 2;

FIG. 4 is a schematic section view taken generally along line 44 of FIG. 2;

FIG. 5 is a side view of a piston of the invention;

FIG. 6 is a front view of the piston of FIG. 5;

FIG. 7 is a view of a control assembly of the invention;

FIG. 8 is a schematic partial longitudinal section view of the shaft of the invention with conduits displaced to aid in the explanation of the invention;

FIG. 9 is a section view taken generally along line 9-9 of FIG. 8',

FIG. 10 is a schematic section view of a valve unit of the invention in a first position;

FIG. 11 is a schematic section view of the valve unit of FIG. 10 in a second position; and

FIG. I2 is a schematic section view of the valve unit of FIG. I in a third position.

Detailed Description Referring to FIG. I, it will be seen that a hydraulic control system of the invention comprises a single drive means or prime mover which drives a single rotor means 22 about a single shaft 24. A plurality of radial pump units 26a, 26b, 26c, and 26d are included in rotor means 22 and are driven therewith. The direction and magnitude of fluid flow from each of the pump units is controlled by corresponding control assemblies 28a, 28b, 28c, and 28d which, as will be presently explained, individually regulate the pump units independently of the remaining pump units and the direction of rotation of the rotor means. Pairs of conduits 30a and 32a, 30b and 32b, 30c and 32c, and 30d and 32d connect radial pump units 26a, 26b, 26c and 26d, respectively, with corresponding valve units 34a, 34b, 34c and 34d. The position of the control assembly for each pump unit will determine whether there will be any fluid flow and, if so, the direction of flow in the corresponding conduits. In any case, the corresponding valve will automatically, in response to the direction of flow in the conduits control the direction of fluid flow to corresponding work units 36a, 36b, 36c and 36d through pairs of fluid paths 38a, and 40a, 38b and 40b, 38c and 406, and 38d and 40d, respectively, in a manner to be presently describedv After fluid is returned from a hydraulic work unit, the fluid will be directed by the corresponding valve to a condenser 42 through a condenser return conduit 41. The purpose of the condenser is to cool the oil and return it through conduit 43 to an oil storage tank 44. Fluid is taken, in turn, from fluid storage tank 44 through conduits 45 and valves 34a, 34b, 34c and 34d to the corresponding radial pump units through one of the corresponding conduits 30a, 30b, 30c and 30d or 32a, 32b, 32c and 32d, depending upon the setting of the corresponding control assembly. Should, however, the control assembly for a particular radial pump unit be in its neutral position, no fluid will flow through either of the corresponding conduits; and the corresponding valve will, as will be presently explained, serve as a locking valve to maintain the corresponding hydraulic work unit in the position to which it was previously adjusted.

Turning to FIG. 2, it will be seen that a hydraulic control unit of the invention includes a closed housing 46. The housing includes a cylindrical outer wall 48, the ends of which are closed by circular end walls and 52, being suitably secured thereto by means of bolts 54. End wall 50 has a central extension 56 extending outwardly therefrom and providing a central bore 53. Likewise, end wall 52 is provided with a central extension 60 extending outwardly in the opposite direction and providing a central bore 62 of the same internal diameter as bore 58. It will be noted that shaft 24 is received in bores 58 and 62 and extends therebetween. It is to be understood that shaft 24 is relatively stationary with respect to housing 46, and appropriate detent means may be provided for this purpose. In order to seal the ends of housing 46, an end plate 64 is secured to the end of end wall extension 56 by means of bolts 66, and an end plate 68 is secured to the end of end wall extension 60 by means of bolts 70. Since it is desirable that the space 72 within housing 46 be filled with oil to surround the operating parts, appropriate sealing gaskets 74 and 76 are provided between end wall 50 and cylindrical outer wall 48 and between end wall 52 and cylindrical outer wall 48, respectively. Similar seating gaskets (not shown) may be provided between end plate 64 and end wall extension 56 and between end plate 68 and end wall extension 60.

As will be noted from FIGS. 2 and 3, rotor 22 is mounted for rotation on stationary shaft 24 and, for this purpose, includes a central bore 78 which is received on shaft 24. Suitable bearing means (not shown) may be provided between rotor 22 and shaft 24 for facilitating the rotation. As particularly shown in FIG. 3, radial pump unit 26a comprises five radial bores 80a extending radially outwardly in substantially the same plane from central bore 78. From FIG. 2 it will be seen that the remaining radial pump units 26b, 26c, and 26d contain substantially identical radial bores 80b, 80c, and 80d, respectively. Each of the radial bores receives a piston mounted for reciprocation therein. Referring to FIG. 3, for example, it will be seen that radial pump unit 260 comprises pistons 82a within radial bores 800. In like manner, as shown in FIG. 2, pistons 82b, 82c and 82d are received in bores 80b, 80c, and 80d, respec tively.

As shown in FIGS. 5 and 6, each of the pistons is provided with a piston extension 34 providing a guide groove 86 defined by an upper lip 88 and inclined surface 90 on the upper end of the main portion of the piston body. Guide grooves 86 are received on a guide ring 92 which also forms the inner race of a ball bearing 94, being freely rotatable thereon. The outer race 96 of the ball bearing is relatively stationary and is received within an adjusting ring 98.

The stroke of the pistons is regulated by the degree of eccentricity of guide ring 92 wich respect to the axis of rotation of rotor 22. When guide ring 92 is concentric with the axis of rotation of rotor 22, the guide groove 86 of the piston will be equidistant from the axis of rotation for all points in the rotation of the rotor; and the pistons will not reciprocate within the bores as the rotor rotates. On the other hand, if guide ring 92 is shifted to become eccentric of the axis of rotation, at different points in the rotary travel of rotor 22 the pistons will be shifted relative to the axis of rotation and will therefore reciprocate within the radial bores. In order to facilitate the adjustment of the eccentricity of guide ring 92, the adjusting rings 98 have adjusting ring extensions 100 provided with adjusting ring extension bores 102 which are dimensioned to receive control cams I04 mounted on control shafts 106. As is most clearly shown in FIG. 7, a control lever 108 is secured by means of a sleeve on one end of control shaft 106. Referring to FIG. 2, it will be noted that control shaft 106 extends through one of end walls 50 and 52 and is associated with an appropriate sealing gasket 112. The other end of shaft 106 is journaled in a lug 107 projecting from the inner surface of wall 48. As will be noted from FIG. 2, each of radial piston units 26a, 26b, 26c and 26d is provided with a corresponding control assembly 28a, 28b, 28c and 28d comprising a guide ring 92, a ball bearing 94, an outer ball bearing race 96, an adjusting ring 98, an adjusting ring extension 100, an adjusting ring extension bore 102, a control cam 104, a control shaft 106, 3. lug I07, a control lever 108, a control lever sleeve 110, and a control shaft gasket I12. Since all the control levers 108 would not normally be seen in the view of FIG. 2, some of these have been shown in phantom lines for purposes of illustration. Thus, it will be apparent that the guide rings of the respective radial pump assemblies may be individually adjusted independently of the adjustment of the remaining guide rings. Although, as illustrated, control levers 108 are to be actuated manually, it is to be understood that the positions of the control levers may be adjusted automatically by providing appropriate linkages to an automatic control system.

In order to limit lateral adjustment of adjusting rings 98 and to maintain them generally concentric of rotor 22, stops 114 may be provided mounted on bolts 116 extending through the wall 48 of housing 46 on each side of the ring. Since stops 114 extend inwardly of wall 48 in close adjacency to adjusting ring 98, they limit the lateral movement thereof, permitting, however, limited adjustment by means of cams 104. Although only a pair of stops 1 14 are shown in FIG. 3, it is to be understood that two such stops are provided for each of the adjusting rings associated with each of the radial pump units.

As already mentioned. rotor 22 is caused to be rotated by a prime mover or motor 20. To this end, as shown most clearly in FIG. 3, a drive shaft 118 is driven by prime mover and drives a driving gear 120. Drive gear 120 meshes with a rotor gear 122 (See FIG. 2) forming an integral part of rotor 23. Due to the unique control assemblies employed with the several radial pump units, there is no need to provide directional control for the prime mover 20 which may drive drive shaft 119 continually in one direction and at a constant speed. All adjustments as to magnitude of flow and direction of flow will be accomplished by suitable adjustment of the corresponding control assembly of a particular radial pump unit independently of the adjustments of the remaining radial pump units.

The manner in which the hydraulic fluid flows to and from the radial pump units will now be described. As will be seen most particularly in FIGS. 2, 3, 8 and 9, shaft 24 is provided with a plurality of conduits leading to and from the radial pump units. A first pair of conduits 124 and 126 at the left-hand end of shaft 24 are associated with radial pump unit 260. A second pair of conduits 128 and 130 at the same end of the shaft are associated with radial pump unit 26b. In like manner, at the opposite end of shaft 24 (see FIG. 2) conduits 132 and 134 lead to and from radial pump unit 26d, while conduits 136 and 138 are associated with radial pump unit 26c. Conduit 124 leads to a port 140 which extends a substantial distance (nearly halfway) around the circumference of shaft 24. Similarly, conduit 126 terminates in a port 142 which extends for the same distance about the remaining half of the circumferential periphery of shaft 24. Ports 140 and 142 are at substantially the same axial position along shaft 24, thus communicating with the radial bores 800 as the rotor rotates thereover. In like manner, conduit 128 terminates in port 144 extending about nearly one half of the periphery of shaft 24 adjacent to the radial bores 80b of radial pump unit 26b, and conduit 130 terminates in port 146 extending over nearly the remaining half of the periphery of shaft 24 adjacent to radial bores 80b. As will be apparent from FIG. 2, similar ports 148 and 150 are in communication with conduits 136 and 138, respectively, and extend about substantial portions of the periphery of shaft 24 adjacent to the radial bores 80c of radial pump unit 26c; and ports 152 and 154 are terminations for conduits 132 and 134, respectively, and communicate with substantial portions of the periphery of shaft 24 adjacent radial ports d of radial pump unit 26d.

The opposite ends of the conduits in shaft 24 comm unicate with one of the valves 34a, 34b, 34c, and 34d, as will be presently described. Thus, conduit 124 communicates with a port 156 extending through valve housing 158 of valve 34a, and conduit 126 communicates with a valve port 160 extending through valve housing 158. In like manner, conduit 128 leads to a valve port 162 extending through valve housing 164 of valve 341), and conduit 130 leads to a valve port 166 extending through this valve housing. Similar connections are found for conduits 132, 134, 136 and 138. Conduit 132 extends to valve port 168 extending through valve housing 170 of valve 34d while conduit 134 is coupled to valve port 172 extending through valve housing 170. Conduit 136 leads to valve port 174 extending through valve housing 176 of valve 34c, and conduit 138 leads to valve port 178 in valve housing 176. The valve housings are suitably secured to the main housing 46 of the hydraulic control unit by means of bolts 180.

With particular reference to FIG. 4, it will be seen that valve 340 includes a spool 182 positioned within a valve chamber 184 provided inside valve housing 158. It will be noted that valve spool 182 comprises enlarged head portions 186, 188, and 192 engaged with the cylindrical surface of valve chamber 184. Valve spool 182 also includes reduced diameter or neck portion 194 between valve heads 186 and 188, 196 between valve heads 188 and 190, and 198 between valve heads 190 and 192. These valve neck portions respectively provide valve recesses 200, 202, and 204 in valve spool 182. The valve housing 158 is also provided with a pair of ports 206 and 208 near each end of the valve chamber 184. These valve ports lead to a common conduit 210 which is connected to a port 212 adapted to be coupled by means of a suitable fitting to the line 45 leading from tank 44, whereby hydraulic fluid may be supplied to the valves from the tank. The valve 34a is also provided with a valve port 214 extending through valve housing 158 to valve chamber 184 at a central portion therealong. Valve port 214 communicates with a conduit 216 leading to a port 218 adapted to be connected by means of a suitable fitting to condenser return conduit 41 (see FIG. 1) leading to fluid condenser 42. As is evident from FIG. 2, a hole 21 1 is provided through end wall 50 from conduit 210 to the space 72 within housing 46 to allow pressure to escape from the system and prevent pressure build up in the housing which might cause the seals to blow.

Valve 34a is also provided with a valve port 220 extending through valve housing 158 which is adapted to be connected by means of an appropriate fitting to line 38a leading to or from a hydraulic work unit 36a. Near port 220 is a port 222 leading to a pop valve 224. An additional valve port 226 is provided through valve housing 158 and is adapted to be connected by means of a suitable fitting to line 40a leading to or from hydraulic work unit 36a. A valve port 228 is located near port 226 and leads to a pop valve 230. Pop valves 224 and 230 are responsive to excessive hydraulic pressure and are adapted to open a path through a conduit 232 to a valve port 234 communicating with valve recess 202, permitting fluid to be by-passed to condenser 42 through valve port 214 and conduit 216.

It is also to be noted that valve spool 182 is provided with a passageway 236 extending from neck 198 and valve recess 204 to the right-hand end of valve head 192. At the other end of valve spool 182 is a similar passage 238 extending from neck I94 and valve recess 200 to the left-hand end of valve head 186.

Valve chamber 184 includes enlarged end portions forming shoulders 240 and 242, and valve blocks 244 and 246 are respectively associated with shoulders 240 and 242 in the enlarged end portions of the chamber. Each of these valve blocks are biased by means of re spective springs 248 and 250 into engagement with the corresponding shoulder. The springs bear respectively against the inner surface of end caps 252 and 254 which include threaded sleeves 256 and 258 respectively which engage internal threads within the valve housing 158. In order to properly position the end caps, they are provided with outwardly extending flanges 260 and 262, respectively, which abut against the corresponding ends of the valve housing 158. Valve block 244 is provided with an aperture 245 in alignment with passage 238, and valve block 246 has an aperture 247 in alignment with passage 236.

The normal position of the valve spool is shown in FIG. 11 with both of the valve blocks 244 and 246 biased into contact with the corresponding shoulders 240 and 242. It will be noted that in this position the valve ports 206 and 208 appear to be blocked by valve heads I86 and 192. However, in order to permit leak-by of fluid to valve recesses 200 and 204 from ports 206 and 208, valve heads 186 and 192 are slightly grooved as indicated at 206A and 208A. The purpose of this arrangement is to permit the pump unit to pick up oil to prime the unit as will become apparent when the operation of the hydraulic control systems is discussed in detail hereinbelow. The leak-bys also serve to keep the pump unit from building up the pressure in the system, permit instant fluid flow, prevent vacuums in the systems when the pump unit is idling, and prevent creeping of the corresponding work unit.

Each of the valves 34a, 34b, 34c and 34d are substantially identical and, accordingly, the remaining valves will not be described in detail. It is to be noted, how ever, that the same reference numerals are employed for the corresponding parts of the valves where they are seen in the drawings.

The operation of the hydraulic control system of the invention will be apparent from detailed consideration of the operation of one of the radial pump units 26a and its associated valve 340, it being understood that the operation of the remaining radial pump units and associated valves will be similar. Let it be assumed, at the outset, that the valve 340 is in its neutral, or starting position, as shown in FIG. 11. The valve spool 182 will be biased by springs 248 and 250 to its mid-position. When the valve spool is in this position, valve blocks 244 and 246 are biased into engagement with corresponding shoulders 240 and 242 and abut the corresponding ends of the valve spool. Valve head 186 is positioned over valve port 206, and valve head 192 is positioned over valve port 208. Valve port 220 is closed by valve head 188, and valve port 226 is closed by valve head 190. However, valve ports 156 and 160 are open, communicating respectively with valve recesses 200 and 204. In like manner, valve port 222 is in communication with valve recess 200, and valve port 228 is in communication with valve recess 204. The path to condenser 42 through valve port 214 and conduit 216 is open from valve recess 202. If, at this time, the control lever 108 of control assembly 28a corresponding with radial pump unit 26a is in its neutral position, guide ring 92 will be concentric with rotor 22 and shaft 24. Under these circumstances, there will be no reciproca' tion of pump pistons 82a, and no pressure will be applied by the hydraulic fluid through conduit 124 and valve port 156 or through conduit 126 and valve port 160. The valve spool 182 will therefore remain in its mid-position, as shown in FIG. 11. Since ports 220 and 226 will be closed by valve heads 188 and 190, the valve 34a will serve as a locking valve to hold the cylinder of hydraulic work unit 36a in its previously attained position.

If, now, control assembly 280 is adjusted by rotating its lever 108 to bring cam 104 into the position shown in FIG. 3 with respect to radial pump unit 26a, the distance A between the lower side of rotor 22 and guide ring 92 will become greater than the distance B between the upper side of rotor 22 and guide ring 92. Guide ring 92 will then be eccentric with respect to rotor 22, causing reciprocation of pump pistons 820 within radial bores a. If it be assumed that rotor 22 is being driven in the direction of arrow E (see FIG. 3), pistons 820 will begin to draw away from shaft 24 as they pass end C of rotor center line C-D. This will cause fluid to be drawn into bore 80a from tank 44 through conduit 45, port 212, conduit 210, valve port 208, the leak-by provided on head 192 of valve spool 182, valve recess 204, valve port 160, conduit I26, and port 142. When a pump bore passes end D of center line C-D, the pump piston 82a will begin to return toward shaft 24 compressing the fluid within the bore and forcing it under pressure out port 140, conduit I24, valve port 156, valve recess 200, through valve passage 238 to the left end of valve chamber 184. This will cause a pressure build-up on the left end of spool 182 causing it to be shifted to the right as shown in FIG. 10. In this position, spring 250 will be compressed, and spring 248 will be extended; valve block 244 will abut against shoulder 240 and be spaced from the end of valve head 186; valve block 246 will have been moved from shoulder 242 and into abutment with the end of sleeve 258. As a consequence of this rightward movement, valve port 220 will now be in communication with valve recess 200. Thus, hydraulic fluid under pres sure will now flow from valve recess 200 through valve port 220 through line 38a to hydraulic work unit 360, from which it will return via line 40a to valve port 226. Should the pressure in valve recess 200 be excessive, pop valve 224 will open permitting fluid to flow through conduit 232 (see FIG. 4) to valve recess 202. As fluid returns from the hydraulic work unit through valve port 226, it is received in valve recess 202 and flows through valve port 214 to conduit 216, from which it flows out port 218 through line 41 to condenser 42. After the hydraulic fluid is cooled in condenser 42, it is returned to rank 44 through line 43.

It is to be noted, that the magnitude of fluid flow is regulated by the length of the stroke of the pistons 82a of radial pump unit 260. The magnitude of flow is a function of the degree of eccentricity of guide ring 92 with respect to rotor 22 as indicated by the relative magnitudes of distances A and B. The flow can be controlled from as little as a few drops per minute for precise control of a cylinder in hydraulic work unit 36a up to the full flow permitted by the speed of rotation of rotor 22 and the capacity of the cylinders of the radial pump unit.

Should it be desired to reverse the direction of flow through hydraulic work unit 360, it is merely necessary to adjust control assembly 280 to reverse the relative size of distances A and B so that guide ring 92 is relatively closer to the undersideof rotor 22 than to the upper side. In this case, as the radial bores 80a of rotor 22 pass point D of center line C-D, pistons 820 will draw away from shaft 24 drawing hydraulic fluid into bore 80a from tank 44 through line 45, port 212, conduit 210, port 206, the leak-by permitted by head 186, valve recess 200, valve port 156, conduit 124, and port 140. When the radial bores pass point C of center line C-D, the pistons 82a return toward shaft 24 compressing the hydraulic fluid and forcing it under pressure out port 142, conduit 126, valve port 160, valve recess 204, and valve passage 236 to the right-hand end of valve chamber 184. This will cause fluid under pressure to act upon the right-hand end of valve spool I82 causing it to move leftward until it attains the position shown in FIG. 12. In this position, spring 248 will be compressed, and spring 250 will be extended. Valve block 244 will abut against the end of sleeve 256, and valve block 246 will abut against shoulder 242. The fluid under pressure in valve recess 204 will be caused to flow out valve port 226, which will now be open, through line 40a to hydraulic work unit 360 and back from hydraulic work unit 36a through line 30a to valve port 220. Should the pressure in valve recess 204 be excessive, pop valve 230 will open and cause the fluid to bypass through conduit 232 (see FIG. 4) to valve recess 202. As fluid is received through valve port 220, it will enter valve recess 202 and be returned through valve port 214, conduit 216, port 218, and line 41 to condenser 42 where it will be cooled before being returned through line 43 to tank 44. As with the other direction of fluid flow through hydraulic work unit 360, the magnitude of flow will be a function of the relative magnitude of distances A and B and may vary from a few drops per minute to the full flow pennitted by the design of the pump.

As will be noted from the foregoing, it is not necessary to reverse the direction of rotation of rotor 22 in order to reverse the direction of flow through a hydraulic work unit. All that is necessary is suitable adjustment of the control assembly to adjust the eccentricity of guide ring 92 with respect to rotor 22 as already described. ln point of fact, various pump units of the system may operate oppositely so that some of the work units operate in one direction, while others of the work units operate in the opposite direction. Moreover, the flow to some work units may be large, while the flow through other work units may be relatively much smaller. A single prime mover rotating in a single direction can thus drive a number of pump units from a single common shaft. Each of the pump units will be individually controlled and independent of the other pump units. The direction of flow from one pump unit through a hydraulic work unit may be opposite to the direction of flow from an adjacent pump unit through another hydraulic work unit with the common shaft driving both pump units still rotating in one direction.

This independent precise flow control and output directional control is a distinct advantage in systems where several motions are desired simultaneously. For example, if a fork lift truck were equipped with a hydraulic control system of the present invention, a load, such as an aircraft engine, could be precisely positioned. The fork lift truck could be used for positioning the aircraft engine for assembly or disassembly from an aircraft. The truck could have separate hydraulic work units, each coupled to a separate pump unit of the invention, and these hydraulic work units could apply up, down, right, left, tilt-up, tilt-down, or rotational motion to the engine for precise alignment of holes or studs without jogging and with smooth movement because of the close control of flow (from a few drops per minute to the full capacity of the pump units). A fork lift truck provided with a hydraulic control system of the present invention could thus readily adjust for lack of surface smoothness and for differing attitudes of the aircraft. ln addition, individual hydraulic work units could be added to each wheel of the truck to provide a fourwheel drive.

in general, hydraulic control systems of the invention are extremely versatile and can be used where rugged precise hydraulic systems are employed or required. For example, there will be considerable utility in tanks, gun turrets, and snow removal equipment. On the other hand, hydraulic control systems of the invention can be incorporated in extremely delicate and precise instru ments or jigs such as are used in radioactive hot cells for positioning specimens for machining, microscopic studies, and the like. Such fixtures could be remotely controlled from outside the hot cell by either mechanical or electric control systems for positioning the control assemblies of the invention.

Although the present invention has been illustrated by an embodiment having four radial pump units, it is to be understood that any number of radial pump units might be employed on a single shaft within the purview of the present invention. Of course, when the number of radial pump units is increased, it will be necessary to increase the capacity of the prime mover, tank, and condenser so that sufficient fluid will be provided under adequate pressures.

While a preferred embodiment of the invention has been shown and described, it will be readily apparent to those skilled in the art that changes can be made without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims. Accordingly, the foregoing embodiment is to be considered illustrative rather than restrictive of the invention, and those modifications which come within the meaning and range of equivalency of the claims are to be included therein.

The invention claimed is:

l. A hydraulic control system comprising: drive means; a stationary shaft, rotor means mounted for rotation about said stationary shaft and driven by said drive means and including a plurality of radial pump units, each pump unit having a plurality of radial bores and a piston in each bore; conduit means for conducting fluid to and from said pump units; said conduit means including a first conduit within said shaft communicating with a first port extending about a first substantial portion of the circumferential portion of the circumference of said shaft and adapted to receive fluid from or supply fluid to said radial bores as said bores pass thereover and a second conduit within said shfat communicating with a second port extending about a second substantial portion of the circumference of said shaft and adapted to receive fluid from or supply fluid to said radial bores as said bores pass thereover, and individual control means for each radial pump unit for adjusting the radial stroke of the pistons of each unit, whereby the direction and magnitude of fluid flow in said conduit means from each of said pump units is controlled independently of the direction and magnitude of flow in the remaining pump units and the direction of rotation of said rotor means, said individual control means comprising a ball bearing race having inner and outer rings with bearings positioned therebetween, said inner ring constituting a guide ring which is capable of rotary movement with respect to said outer ring, the outer extremity of said pistons being interengaged with said guide ring, and means for adjusting the eccentricity of said guide ring with respect to the axis of rotation of said rotor means.

2. A hydraulic control system as recited in claim 1 in which said ball bearing race is held within an adjusting ring and cam means carried by a control lever is provided for shifting said adjusting ring relative to the axis of rotation of said rotor means.

IF i I 

1. A hydraulic control system comprising: drive means; a stationary shaft, rotor means mounted for rotation about said stationary shaft and driven by said drive means and including a plurality of radial pump units, each pump unit having a plurality of radial bores and a piston in each bore; conduit means for conducting fluid to and from said pump units; said conduit means including a first conduit within said shaft communicating with a first port extending about a first substantial portion of the circumferential portion of the circumference of said shaft and adapted to receive fluid from or supply fluid to said radial bores as said bores pass thereover and a second conduit within said shfat communicating with a second port extending about a second substantial portion of the circumference of said shaft and adapted to receive fluid from or supply fluid to said radial bores as said bores pass thereover, and individual control means for each radial pump unit for adjusting the radial stroke of the pistons of each unit, whereby the direction and magnitude of fluid flow in said conduit means from each of said pump units is controlled independently of the direction and magnitude of flow in the remaining pump units and the direction of rotation of said rotor means, said individual control means comprising a ball bearing race having inner and outer rings with bearings positioned therebetween, said inner ring constituting a guide ring which is capable of rotary movement with respect to said outer ring, the outer extremity of said pistons being interengaged with said guide ring, and means for adjusting the eccentricity of said guide ring with respect to the axis of rotation of said rotor means.
 2. A hydraulic control system as recited in claim 1 in which said ball bearing race is held within an adjusting ring and cam means carried by a control lever is provided for shifting said adjusting ring relative to the axis of rotation of said rotor means. 